Bead chains or bead belt drives are well known in the art as providing inexpensive and exceptionally flexible drives between sprocket wheels used in numerous environments, as radio timers, chart drives, vending machines, light-duty conveyors and the like. The use of a bead chain is often desirable in that it can turn multiple corners in various planes, flex easily about narrow radius pulleys, and be readily assembled or replaced, for example. The bead chains are commonly made of metal or plastic beads depending upon strength, quietness and other characteristics, the beads being interconnected by short pin lengths forming small universal joints, or by endless flexible cords, for example. The same are commercially available from many suppliers, such as Voland Corp. of New Rochelle, N.Y.
Heretofore, however, while the bead belts or chains are readily fabricated, the sprocket pulleys over which the chains are trained have presented a greater manufacturing problem requiring multiple complex stampings, expensive diecast metal sprockets, or precisely molded plastic sprockets of material such as nylon, for example. In each instance, however, the periphery of the sprocket must be carefully controlled during fabrication to provide uniform pitch pockets within which the bead stretches are received in training thereabout.
It is readily evident to illustrate one aspect of manufacturing problems and inventory costs, that a separate precision casting or molding must be made with a carefully configured pocketed periphery for each slight variance in sprocket diameter in any range of sizes, with resultant die and tooling expense.